This invention relates in general to wireless communication systems, and more specifically to a method and apparatus in a wireless communication system for facilitating detection of, and synchronization with, a predetermined synchronization signal selected from a plurality of different synchronization signals.
Prior art digital wireless communication systems have utilized fixed synchronization codes for synchronizing receiver timing with that of a received signal. Such synchronization codes have been transmitted either at predetermined intervals or following a preamble. Because a fixed synchronization code does not change from transmission to transmission, the transmitted energy of the synchronization code does not change. Thus, the synchronization code can be detected by simply locating a cross-correlation peak between the fixed synchronization code and the received signal.
Some recently proposed systems, such as Bluetooth, utilize non-fixed synchronization codes. The non-fixed synchronization codes, also referred to as access codes, combine addressing and synchronization in a single, longer code. An access code is assigned on a temporary basis to a receiver. These codes vary significantly in energy from one synchronization code to another, thus making it difficult to reliably detect a wanted synchronization signal while avoiding a false detection on an unwanted synchronization code, or a false detection on pure noise.
Thus, what is needed is a method and apparatus in a wireless communication system for facilitating detection of, and synchronization with, a predetermined synchronization signal selected from a plurality of different synchronization signals. Preferably, the method and apparatus will operate reliably with synchronization signals having a wide range of energy levels and will not false on noise or on unwanted synchronization codes.